>I was happy to see this thread develop.  I am also just moving into the
>confocal stages of a microbial ecology project (also utilizing ssu rRNA
>probes).
>None of the previous replies has mentioned the depth of field trade off one
>suffers when increasing magnification. I am under the impression that
>because 63x objective provides greater depth of field one can afford fewer
>steps along the z-axis. I assume this saves time in imaging and analysis
>and, obviously, memory.
>Do these assumptions hold or is my confocal inexperience showing?
>
>Kevin Brent Smith
>University of Louisville Biology Dept.


Sorry Kevin,

That formula doesn't work in confocal (or, really, in widefield either, if
you enlarge to the same final mag and preserve a reasonable definition of
"depth-of-field".).

In confocal, the z-resolution (i.e. "depth-of-field") varies inversely with
NA-squared.

Cheers,

Jim Pawley

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Prof. James B. Pawley,                             Ph.  608-263-3147
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"A scientist is not one who can answer questions
but one who can question answers."
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